This is the renewal of the Women and Infants Transmission Study at the University of Puerto Rico, Medical Sciences Campus. In this third period of funding, the applicants state that their main objectives are to continue the development of abstracts and the advancement of sub-studies. Additionally, they expect to fortify the site at Ponce, in coordination with the Department of Health officials of the region. The catchment area has already been expanded island wide. They state that their WITS has been successful in complying with all the protocol and subprotocol requirements. They have a cumulative enrollment of 320 women and 261 infants. Puerto Rico is the site with the largest number of women and infant pairs, as well as a site with an excellent retention rate. The implementation of an Interdisciplinary Intervention Model constituted by the investigators, nurses, coordinator, administrative staff, physicians and social workers has been successful in maintaining the mother-infant binomial as a unit for continuous follow-up. The investigators state that they have been participating in the WITS since the beginning, showing a remarkable capacity in the implementation of all protocol requirements. They have the capability to continue enrolling and retaining an increasing number of pregnant women annually. The WITS in Puerto Rico is highly committed to closely link our cohorts to perinatal ACTU studies as well as pediatric ACTU projects.